The present invention generally relates to venting, exhaustion and/or admission of air in piping systems. More specifically, the present invention relates to a system and a method for controlling the entrance of water into a pipeline and its associated venting system when an area surrounding the same is flooded.
It is, of course, generally known to provide check valves. For example, a floatable check valve is disclosed in U.S. Pat. No. 3,620,240 to Bogdanski. Bogdanski discloses a double check valve vent in which floatable valves are positioned in a vent line to be floated up against a valve set when fluid flows outwardly from the tank or flows inwardly toward the tank. The floatable valves, in the absence of fluid, are each spaced a substantial distance from their respective seats so that fumes venting from the tank may move freely with a complete absence of back pressure. The vent pipe of Bogdanski is particularly applicable for use with fuel tanks on boats wherein it is important to prevent the flow of water through the vent line into the fuel tank to prevent the flow of gasoline or fuel oil out of the vent line and onto the boat where it potentially may present a fire hazard.
However, the arrangement illustrated by Bogdanski has its drawbacks. First, the arrangement is designed for routine venting of a tank and does not provide the flow capacity or characteristics needed for protecting piping systems from over and under pressurization. The valve also lacks sealing features to positively prevent the entrance of outside fluid. Therefore, the check valve has limited adaptability for various applications.
A need, therefore exists for an improved air valve with a liquid flow device capable of protecting piping systems for adverse pressure conditions and the entrance of external fluids. Further, because of the critical application of the valve, a provision for field testing is needed.